Recently, a secondary battery capable of charging and discharging has been widely used as an energy source for wireless mobile devices. Also, the secondary battery is attracting attention as a power source for electric vehicles (EVs) and hybrid electric vehicles (HEVs), which are proposed as solutions for air pollution of existing gasoline vehicles and diesel vehicles using fossil fuels.
In small mobile devices, one or a few battery cells are used per device, but middle-sized or large-sized devices such as automobiles uses a middle-sized or large-sized battery module in which a plurality of battery cells are electrically connected, due to the need for high power large capacity, or uses a battery pack in which a plurality of battery modules are connected.
The middle-sized or large-sized battery module is preferably manufactured in a small size and weight, and thus rectangular batteries or pouch-type batteries which may be stacked with a high degree of integration and have a small weight compared with the capacity are frequently used as battery cells applied to the middle-sized or large-sized battery module.
Also, in order for the middle-sized or large-sized battery module to provide the output and capacity demanded for a device or instrument, a plurality of battery cells should be electrically connected in series, in parallel, or both in series and in parallel, and a stable structure should be maintained against external force.
Since the middle-sized or large-sized battery module is composed of a combination of a plurality of battery cells, if over-voltage, over-current or over-heating occurs at some battery cells, a sensing unit should be essentially provided to sense and control the same.
For example, the battery cells in the battery module may be electrically connected in series, in parallel, or both in series and in parallel, by welding their electrode tabs to a plurality of bus bars provided in a metal plate form. In addition, the sensing unit may include a sensing member connected to the plurality of bus bars in a snap-fit manner, a wire connected to each sensing member, and a sensing connector. The sensing unit may be individually connected to the battery cells to provide voltage/current information of the battery cells to a battery management system (BMS) or the like.
Meanwhile, the sensing connector may be connected to a connection socket provided on a BMS board as a counterpart or may be connected to a male connector. Here, the other side of the male connector may be connected to the connection socket on the BMS board. However, the sensing connector is hung on the end of the flexible wire before the battery module and all electrical components including the BMS are assembled, which interferes with assembling of the product.
For example, a housing of the battery module may be configured so that several parts may be assembled thereto, but the wire and sensing connector move during the assembling process, which makes it very inconvenient to assemble the parts. In addition, after the battery cells are received in the housing, while the electrode tabs of the battery cells are welded to the bus bars, the positions of the wire and the sensing connector may interfere with the welding, which may cause welding failure. In addition, after the battery module is completely assembled, wires and sensing connectors not fixed at specific positions are aesthetically not agreeable, and the wires may become tangled. In this case, it may be troublesome to connect the sensing connector to a counterpart.